Intestinal Flora and Nutrient Absorption after Intestinal Resection

Intestinal resection results in loss of surface area, motor disruption, and an altered luminal milieu, all of which might influence bacterial growth. Our aim was to determine the effect of extensive intestinal resection in the dog on small intestinal bacterial flora and nutrient absorption. Ten dogs underwent 75% proximal intestinal resection and were killed at either 12 or 40 weeks. Five animals underwent transection alone and were killed at 12 weeks. Ileal aspirates were cultured. Nutritional status and nutrient absorption were measured every 4 weeks. Mean total and anaerobic ileal flora were increased after resection, significantly at 40 weeks. Overall, more cultures from resected animals had more than 5 × 10⁶ total bacteria (6 of 10 vs. 0 of 10, P <0.05) and more than 10⁵ anaerobic bacteria (5 of 10 vs. 0 of 10, P <0.05) than unoperated animals. Total but not anaerobic bacteria were increased after transection alone. Ingestion and absorption of carbohydrate decreased but absorption efficiency was maintained. Nitrogen intake decreased but excretion and absorption were unchanged. Fat intake decreased and excretion was unchanged resulting in decreased absorption. Mean intake, excretion, and absorption of nutrients were not influenced by the presence of significant growths of total (>5 × 10⁶/ml) or anaerobic (>10⁵/ml) bacteria. It was concluded that (1)75% proximal intestinal resection results in significantly more aerobic and anaerobic bacteria in the ileal remnant; (2) intestinal bacterial content does not correlate with absorption of nutrients; and (3) the colon, and particularly colonic bacteria, may have a more important role in nutrient absorption than luminal flora in the small intestine after resection.